Connect the iPhone to a computer with a USB cable
Open Finder on Mac or iTunes on Windows or older macOS
iPhone 8 or later: press and quickly release Volume Up, press and quickly release Volume Down, then press and hold the Side button until the recovery mode screen appears
iPhone 7 or iPhone 7 Plus: press and hold the Side button and Volume Down button at the same time until the recovery mode screen appears
iPhone 6s or earlier: press and hold the Home button and the Side or Top button at the same time until the recovery mode screen appears
Keep holding the buttons until the cable and computer icon appears on the iPhone screen
Release the buttons when the recovery mode screen appears